A comprehensive study of human and canine benign prostatic hyperplasia (BPH) will be conducted to further our understanding of the etiology, prevention and treatment of this disease. Animal models will be evaluated to ascertain their advantages and limitations as predictive systems for the study of the human disease. Both human and canine BPH will be more clearly defined at the tissue, cellular and molecular levels. The etiological role of steroids will be evaluated in induction and onset of canine BPH. Information will be obtained on the effects of hormones on specific types of cells within the prostate. Age-related changes will be evaluated in both the testes and prostate of the man, dog and rat. Age-matched studies are designed to elucidate the presence of specific factors accompanying the onset and development of BPH in the dog and man. Protocols are designed to evaluate factors that prevent the development of BPH in the dog and to assess various therapeutic modalities in treating and controlling the established disease. New analytical procedures are proposed to facilitate the study of steroid transformation in prostatic tissue. Novel inhibitors will be designed, synthesized and evaluated as specific and irreversible inhibitors of important enzymes of steroid biotransformation.